WO2022118224A1

WO2022118224A1 - Satellite dynamic constraints

Info

Publication number: WO2022118224A1
Application number: PCT/IB2021/061198
Authority: WO
Inventors: Peter Ashwood-Smith; Mehdi Arashmid AKHAVAIN MOHAMMADI
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2020-12-01
Filing date: 2021-12-01
Publication date: 2022-06-09
Also published as: US20220173797A1; CN116508352A

Abstract

A method is provided for setting an attribute of a link between an aerial network node and another node. The method comprises determining that a geographic condition of the link in relation to the aerial network node is satisfied. The method further comprises setting at least one attribute of the link to match at least one attribute associated with the geographic condition. Further, an aerial network node is provided including a network interface, a processor, and a non-transient computer readable memory for storing instructions which when executed by the processor configure the aerial network node to determine that a geographic condition of a link between the aerial network node and another node, in relation to the aerial network node is satisfied. The network node is further configured to set at least one attribute of the link to match at least one attribute associated with the geographic condition.

Description

SATELLITE DYNAMIC CONSTRAINTS

CROSS-REFERENCE TO RELATED APPLICATIONS OF THE INVENTION

[0001] This patent application claims the benefit of priority of United States Patent Application Serial No. 17/108,226 filed December 1, 2020 and entitled “SATELLITE DYNAMIC CONSTRAINTS”, which is hereby incorporated by reference as if reproduced in its entirety.

FIELD

[0002] The present invention pertains to wireless communications networks, and in particular to methods and devices for setting at least one attributes of a link traffic engineering for a wireless communication network while network nodes of a wireless communication network are moving in a predictable manner such as in constellation of satellites.

BACKGROUND

[0003] A satellite network (or constellation of satellites) in non-geosynchronous orbits, which includes inter-satellite links (ISLs) between satellites, will see the links status and characteristics between satellites change as the satellites move around the Earth. It is noted that satellites change directions (relative to the Earth) at polar traversal. Similarly, downward facing links (which refers to links between a satellite in the satellite network and ground stations), or upward facing links (which refers to links between a satellite in the satellite network and satellites in higher layer constellations such as medium earth orbits (MEOs) or geosynchronous satellites (GEOs)) will also experience status and characteristics changes over time. The position, distance and quality of the link will vary as the satellite moves, and it will be subjected to predictable “almanac” based up/down events. This makes traffic engineering for a satellite network much more complicated than traffic engineering for ground based networks. Especially when the engineering desired is relative to the Earth’s surface.

[0004] Link state protocols carry metrics associated with a given link in a satellite network which are used to tune the paths used for routing that result from traffic engineering. The metrics associated with a given link in a satellite network can be used as minimization criteria in a Dijkstra or other type of graph computation to tune the paths used for routing that result from traffic engineering. An example of this is the open shortest path first (OSPF) or intermediate system-to-intermediate system (ISIS) link weight, where the shortest path is defined as the minimum sum of link weights. Attributes of links in a satellite network can also be used to exclude or include certain links. For example, the OSPF opaque attribute can carry link “colors,” which allow paths for routing traffic in the satellite network to be computed that include/exclude only links of a given color. Attributes of links the primary inputs for traffic engineering computations, which are used by various traffic engineering protocols to compute paths for routing traffic in static networks.

[0005] Accordingly, there is a need for methods and devices for traffic engineering techniques for networks of infrastructure nodes in which some infrastructure nodes move relative to the Earth that are not subject to one or more limitations of the prior art.

[0006] This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.

SUMMARY

[0007] An object of aspects of the present invention is to provide methods and devices for techniques for aerial node link based traffic engineering. An aerial network node is an infrastructure node (one which relays traffic (e.g. packets)) in a satellite network which moves relative to the Earth.

[0008] An aspect of the disclosure provides for a method of setting an attribute of a link between an aerial network node and another node. The method comprises determining that a geographic condition of the link in relation to the aerial network node is satisfied. The method further comprises setting at least one attribute of the link to match at least one attribute associated with the geographic condition. In some embodiments the geographic condition of the aerial network node is one of a position of the aerial network node, a coverage area of the aerial network node, a geographic location of the link between the aerial network node and the another node, and a geographic location of at least a portion of the link between the aerial network node and the another node. In some embodiments the geographic condition of the aerial network node is satisfied by at least one of a predicted movement of the aerial network node as a function of time, a cartographic region on Earth, and a region defined by a mathematical function. In some embodiments the aerial network node is a satellite and the another node includes one of a ground station, and another satellite. In some embodiments the determining step is carried out by one of a ground station, and a satellite. In some embodiments the setting step is carried out by one of a ground station, and a satellite. In some embodiments the at least one attribute includes one of a downlink link attribute, an inter-satellite link (ISL) attribute, and a general operational attribute. In some embodiments the at least one attribute includes a link attribute including at least one of an intermediate system-to-intermediate system (ISIS) attribute, an open shortest path first (OSPF) attribute, a frequency attribute, a power attribute, a coding attribute, and a ground station address attribute. In some embodiments the geographic condition of the aerial network node is satisfied by at least one of a location of the aerial network node with respect to the Earth, or another set of infrastructure nodes at a higher or lower orbit; a location of the existing link with respect to the Earth, or another set of infrastructure nodes at a higher or lower orbit; or a location of at least a portion of the existing link with respect to the Earth, or another set of infrastructure nodes at a higher or lower orbit. In some embodiments setting at least one attribute of the link to match at least one attribute associated with the geographic condition includes creating a new link between the aerial network node and the another node having the at least one attribute. In some embodiments the link is and existing link, and setting at least one attribute of the link to match at least one attribute associated with the geographic condition includes modifying the existing link.

[0009] Another aspect of the disclosure provides for an aerial network node including at least one network interface, at least one processor, and a non-transient computer readable memory for storing instructions which when executed by the at least one processor configure the aerial network node to determine that a geographic condition of a link between the aerial network node and another node, in relation to the aerial network node is satisfied. The network node is further configured to set at least one attribute of the link to match at least one attribute associated with the geographic condition. In some embodiments the geographic condition of the aerial network node is one of a position of the aerial network node, a coverage area of the aerial network node, a geographic location of the link between the aerial network node and the another node, and a geographic location of at least a portion of the link between the aerial network node and the another node. In some embodiments the geographic condition of the aerial network node is satisfied by at least one of a predicted movement of the aerial network node as a function of time, a cartographic region on Earth, and a region defined by a mathematical function. In some embodiments the aerial network node is a satellite and the another node includes one of a ground station, and another satellite. In some embodiments the determining step is carried out by one of a ground station, and a satellite. In some embodiments the setting step is carried out by one of a ground station, and a satellite. In some embodiments the at least one attribute includes one of a downlink link attribute, an intersatellite link (ISL) attribute, and a general operational attribute. In some embodiments the at least one attribute includes a link attribute including at least one of an intermediate system-to- intermediate system (ISIS) attribute, an open shortest path first (OSPF) attribute, a frequency attribute, a power attribute, a coding attribute, and a ground station address attribute. In some embodiments the geographic condition of the aerial network node is satisfied by at least one of a location of the aerial network node with respect to the Earth, or another set of infrastructure nodes at a higher or lower orbit; a location of the existing link with respect to the Earth, or another set of infrastructure nodes at a higher or lower orbit; or a location of at least a portion of the existing link with respect to the Earth, or another set of infrastructure nodes at a higher or lower orbit. In some embodiments setting at least one attribute of the link to match at least one attribute associated with the geographic condition includes creating a new link between the aerial network node and the another node having the at least one attribute. In some embodiments the link is and existing link, and setting at least one attribute of the link to match at least one attribute associated with the geographic condition includes modifying the existing link.

BRIEF DESCRIPTION OF THE FIGURES

[0010] Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

[0011] FIG. 1 depicts a method of setting an attribute of a link between an aerial network node and another node, according to embodiments of the present invention.

[0012] FIG. 2 depicts an example illustration of movement of a link between two nodes as a function of time, according to embodiments of the present invention.

[0013] FIG. 3 depicts an example region having a shaded sub-region that is subject to aerial network node links, according to embodiments of the present invention. [0014] FIG. 4 is a block diagram of an electronic device that may be used for implementing devices and methods in accordance with representative embodiments of the present invention.

[0015] It will be noted that throughout the appended drawings, like features are identified by like reference numerals.

DETAILED DESCRIPTION

[0016] Wireless communication networks comprising network nodes (e.g. aerial network nodes and ground stations) are generally represented using graphs that includes nodes and edges. Each node of a graph represents a network node of a wireless communication network, and each edge of the graph represents a link between two network nodes. The graph has attributes associated with each node of the graph and each edge of the graph. Traffic engineering is generally performed using the attributes of the nodes and edges. Link State Protocols use the attributes of the nodes and edges of the graph to compute paths used for in a wireless communication network.

[0017] FIG. 1 depicts a flowchart of a method 100 of setting at least one attribute of a link between an aerial network node and another node in a satellite network. The method 100 may be implemented in software. The method 100 may be carried out when computer-readable code or instructions of the software is executed by a processor of an electronic device, such as processor 404 of an electronic device 400 (see FIG. 4). The software (i.e. the computer- readable code or instructions) may be stored on a computer-readable medium. The method 100 begins, at step 102. At step 102, the method 100 determines that a geographic condition of the link in relation to the aerial network node is satisfied. The method then proceeds to step 104. At step 104, the method 100 sets at least one attribute of the link to match at least one attribute associated with the geographic condition of the link in relation to the aerial network node. Traffic engineering may thus be defined relative to the surface of the Earth, and traffic engineering may be performed by the electronic device 400 to automatically adjust routes for traffic in the satellite network based on attributes of the link where at least one attribute of the link is set to match at least one attribute associated with a geographic condition in relation to aerial network node.

[0018] In some embodiments of the method 100, the geographic condition of the link in relation to the aerial network node can include one of a position of the aerial network node relative to a geographic region, a coverage area of the aerial network node relative to a geographic region, a geographic location of the link between the aerial network node and the another node, and a geographic location of at least a portion of the link between the aerial network node and the another node. A geographic location of coordinates of the center of the link, coordinates of a location of one end of the link, or a coordinates of bounding box that spans the link. The geographic condition may therefore be determined to be satisfied at step 102 of the method 100 when the aerial network node physically moves, when changes in the coverage area of the aerial network node relative to a geographic region are detected, or when changes in a geographic location of the link, or at least a portion of the link, are detected.

[0019] In some embodiments of the method 100, the geographic condition of the aerial network node is determined to be satisfied at step 102 when a predicted movement of the aerial network node as a function of time overlaps or intersects a cartographic region on Earth or a region generated by a mathematical function. A predicted movement of the aerial network node may include using an almanac to predict where the aerial network node may be at any given time. A cartographic region on Earth may include villages, towns, cities, states, provinces or even entire nations or continents. At least one attribute of the link may be set to match at least one of the attribute of the geographic condition based on when an aerial network node enters or leaves a particular constraint region. Similarly, constraint regions may be generated using mathematical functions. Constraint regions generated this way may include regular polygons, circles, ellipses, or the like.

[0020] In some embodiments of the method 100, the aerial network node is a satellite and the another network node is one of a ground station and another satellite. In some embodiments of the method 100, both the aerial network node and the another network node are satellites, and the link between the two satellites (i.e. the aerial network node and the another network node) is an inter-satellite link (ISL).

[0021] In some embodiments of the method 100, the step 102 of the method 100 is carried out by one of a ground station, and a satellite. In some embodiments, the step 104 of the method 100 is carried out by one of a ground station and a satellite. Different ground stations may possess different levels of authority. For example, an operator of a ground station may possess only limited abilities to modify characteristics of the satellite, while an operator of a satellite may possess full, unrestricted capabilities to modify characteristics of a satellite. [0022] In some embodiments of the method 100, the at least one attribute of the link includes one of a downlink link attribute, an inter-satellite link (ISL) attribute, and a general operational attribute. Changes to a downlink link attribute may be defined independent of a constellation of aerial nodes and may be used to match regions where regulatory constraints exist. Step 104 of the method 100 may therefore set a downlink link attribute as an aerial network node moves from constraint region to constraint region.

[0023] Similarly, in some embodiments of the method 100, an attribute of the link may be an intermediate system-to-intermediate system (ISIS) attribute, an open shortest path first (OSPF) attribute, a frequency attribute, a power attribute, a coding attribute, and a ground station address attribute. At least one attributes of the link may be set to match the at least one attribute associated with the geographic condition using a script which is executed when it is determined that the geographic condition of the link relative to the aerial network node has been satisfied.

[0024] In some embodiments of the method 100, the geographic condition of the link in relation to the aerial network node is satisfied by at least one of a location of the aerial network node with respect to the Earth, or another set of infrastructure nodes at a higher or lower orbit; a location of the link with respect to the Earth, or another set of infrastructure nodes a higher or lower orbit; or a location of at least a portion of the existing link with respect to the Earth, or another set of infrastructure nodes at a higher or lower orbit. Thus, in some embodiments of the method 100, minor modifications to Link State Protocols resulting from setting at least one attribute of the link is set to match at least one attribute associated with the geographic condition and existing route computations may be used to provide for traffic engineering in space.

[0025] In some embodiments of the method 100, at step 104 at least one attribute of the link is set to match at least one attribute associated with the geographic condition by creating a new link between the aerial network node and the another node having the at least one attribute.

[0026] In some embodiments of the method 100, at step 104 at least one attribute of the link is set to match at least one attribute associated with the geographic condition by modifying the link between the aerial network node and the another node. [0027] In some embodiments, the aerial network node may be configured to determine that a geographic condition of a link, or at least a portion of a link, between the aerial network node and another node, in relation to the aerial network node is satisfied. The aerial network node is further configured to set at least one attribute of the link to match at least one attribute associated with the geographic condition.

[0028] FIG. 2 depicts an example illustration 200 of movement of a link 206 between two aerial network nodes, 202a and 202b, as function of time. Arrow 208 defines the direction of movement of both the aerial network nodes 202a and 202b, and the link 206. As the link 206 passes over a first region 204a, the attributes of the link 206 may change. Another change may occur in the attributes of the link 206 as the link 206 passes over a second region 204b.

[0029] In FIG. 2, regions 204a and 204b may be called constraint regions on the surface of the earth, as they may be contained in a polygon, ellipse or circle mapped to the surface of the Earth. Each vertex of the polygon or focal point may be defined as the latitudinal and longitudinal coordinates of that point or, similarly, its X-Y-Z coordinates. When the link 206 between aerial network nodes 202a and 202b intersects a particular constraint region (i.e., passes over a particular constraint region), attributes of the link 206 associated with the constraint region are set (e.g. inherited) as described in step 104 for the purposes of routing computations by any node (e.g. aerial network nodes 202a, 202b) which sees the link 206 and the attributes of the link 206 are used by the aerial network node 202a in its routing computations.

[0030] Moreover, when an aerial network node 202a, 202b enters a constraint region (i.e., passes over a constraint region), the attributes associated with that constraint region may be se the aerial network nodes 202a, 202b. In particular, the attributes of the link 206 associated with the constraint region may be for downlink control. The attributes of the link 206 associated with the constraint region for downlink control may include a frequency attribute (e.g. radio frequency used for downlink control), a power attribute (e.g. a power used to generate the radio frequency, a coding attribute (e.g. an indication of a type of waveform to be used for downlink control, number of subcarriers, any gaps, etc.) or aground station attribute. Thus a form of “satellite slicing” is provided.

[0031] Referring now to FIG. 3, some possible advantages of the method 100 of the present disclosure will be discussed. FIG. 3 depicts a region 302 having a shaded sub-region 304. As an example scenario, there may be a corridor between two major cities that carries important traffic which will follow explicit routes pre-computed by ground stations (e.g. base stations). Therefore, it would be undesirable to have best effort traffic use those explicit routes. Instead, links 206 along the corridor between the cities has higher metrics for best effort traffic. In order to accomplish this, the sub-region 304 may be defined along the corridor to force the link metrics to be different when a link 206 crosses the sub-region 304 but to return to normal everywhere else in the corridor. In this manner, traffic routed using Shortest Path First (SPF) algorithms will not be routed through this corridor (sub-region 304) if at all possible. Purely as an example, in FIG. 3, aerial network nodes, such as aerial network nodes 202a, 202b, are represented by the filled black circles.

[0032] The sub-regions 304 and actions within the regions 302 may be defined with a script written using a scripting language to increase the granularity of options within the regions. A region, such as region 302 may be defined with a set of bounding points. A region, such as region 302, may be associated with actions where actions can have conditions. For example:

[0033] In Region <ptl, pt2, p3, p4>

Between 10:00Zulu and 15:00Zulu

When Sat.direction > XXX degrees

Set Sat.link[WEST] .metric = 100

[0034] In this regard, a region, such as region 203 may also be used to control downlink frequencies and properties so that proper regulations for downlink frequency, power or coding may be used in various different regions. A script writing in a scripting language may include functions that return information including a global time, hardware health indicators, or link statuses. A script may also include further downlink attributes, such as encryption options.

[0035] A script may be a union of a set of uploads of different scripts from a plurality of sources but where rules as to which reference frames may be defined by which sources is enforced to prevent unauthorized reference frame control

[0036] FIG. 4 is a block diagram of an electronic device (ED) 400 that may be used for implementing the methods disclosed herein, including the method 100. The person having skill in the art will reasonably appreciate that an aerial network node may be an ED 402, and that the method 100 disclosed herein may be executed on the ED 402 (e.g. the aerial network node). In some embodiments, the ED 402 may be an element of communications network infrastructure, such as a ground station (i.e. a base station), for example a NodeB, an enhanced Node B (eNodeB), a next generation NodeB (sometimes referred to as a gNodeB or gNB), a home subscriber server (HSS), a gateway (GW) such as a packet gateway (PGW) or a serving gateway (SGW) or various other nodes or functions within an evolved packet core (EPC) network. In other embodiments, the ED 402 may be a device that connects to network infrastructure over a radio interface, such as a mobile phone, smart phone or other such device that may be classified as a User Equipment (UE). In some embodiments, ED 402 may be a Machine Type Communications (MTC) device (also referred to as a machine-to-machine (m2m) device), or another such device that may be categorized as a UE despite not providing a direct service to a user. In some references, an ED 402 may also be referred to as a mobile device, a term intended to reflect devices that connect to mobile network, regardless of whether the device itself is designed for, or capable of, mobility. In some embodiments, ED 402 may be an aerial network node such as a satellite. Specific devices may utilize all of the components shown or only a subset of the components, and levels of integration may vary from device to device. Furthermore, an ED 402 may contain multiple instances of a component, such as multiple processors, memories, transmitters, receivers, etc. The ED 402 typically includes a processor 404, such as a Central Processing Unit (CPU), and may further include specialized processors, a memory 406, a network interface 408 and a bus 410 to connect the components of ED 402. ED 402 may optionally also include components such as a mass storage device 412 (shown in dashed lines).

[0037] The memory 406 may comprise any type of non-transitory system memory, readable by the processor 404, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or a combination thereof. In an embodiment, the memory 106 may include more than one type of memory, such as ROM for use at boot-up, and DRAM for program and data storage for use while executing programs. The bus 410 may be one or more of any type of several bus architectures including a memory bus or memory controller, a peripheral bus, or a video bus.

[0038] The ED 402 may also include one or more network interfaces 408, which may include at least one of a wired network interface and a wireless network interface. As illustrated in FIG. 4, network interface 408 may include a wired network interface to connect to a network 418, and also may include a radio access network interface 420 for connecting to other devices over a radio link. When ED 402 is network infrastructure, the radio access network interface 420 may be omitted for nodes or functions acting as elements of the Core Network (CN) other than those at the radio edge (e.g. an eNB). When ED 402 is infrastructure at the radio edge of a network, both wired and wireless network interfaces may be included. When ED 402 is a wirelessly connected device, such as a User Equipment, radio access network interface 420 may be present and it may be supplemented by other wireless interfaces such as WiFi network interfaces. The network interfaces 408 allow the ED 402 to communicate with remote entities such as those connected to network 418.

[0039] The mass storage 412 may comprise any type of non-transitory storage device configured to store data, programs, and other information and to make the data, programs, and other information accessible via the bus 410. The mass storage 412 may comprise, for example, one or more of a solid state drive, hard disk drive, a magnetic disk drive, or an optical disk drive. In some embodiments, mass storage 412 may be remote to the ED 402 and accessible through use of a network interface such as interface 408. In the illustrated embodiment, mass storage 412 is distinct from memory 406 where it is included, and may generally perform storage tasks compatible with higher latency, but may generally provide lesser or no volatility. In some embodiments, mass storage 412 may be integrated with a heterogeneous memory 406.

[0040] In some embodiments, ED 402 may be a standalone device, while in other embodiments ED 402 may be resident within a data center. A data center, as will be understood in the art, is a collection of computing resources (typically in the form of servers) that can be used as a collective computing and storage resource. Within a data center, a plurality of servers can be connected together to provide a computing resource pool upon which virtualized entities can be instantiated. Data centers can be interconnected with each other to form networks consisting of pools computing and storage resources connected to each by connectivity resources. The connectivity resources may take the form of physical connections such as Ethernet or optical communications links, and in some instances may include wireless communication channels as well. If two different data centers are connected by a plurality of different communication channels, the links can be combined together using any of a number of techniques including the formation of link aggregation groups (LAGs). It should be understood that any or all of the computing, storage and connectivity resources (along with other resources within the network) can be divided between different subnetworks, in some cases in the form of a resource slice. If the resources across a number of connected data centers or other collection of nodes are sliced, different network slices can be created.

[0041] Although the methods and devices of the present disclosure have been described with respect to satellite networks, the methods and devices may be used for setting in any wireless communication network, such as a radio access network or a Wi-Fi network, in which network nodes move in a predicable manner. [0042] Although the present invention has been described with reference to specific features and embodiments thereof, it is evident that various modifications and combinations can be made thereto without departing from the invention. The specification and drawings are, accordingly, to be regarded simply as an illustration of the invention as defined by the appended claims, and are contemplated to cover any and all modifications, variations, combinations or equivalents that fall within the scope of the present invention.

Claims

CLAIMS:

1. A method of setting at least one attribute of a link between an aerial network node and another network node, the method comprising: determining that a geographic condition of the link between the aerial network node, and the another node, in relation to the aerial node, is satisfied; setting at least one attribute of the link to match at least one attribute associated with the geographic condition.

2. The method of claim 1, wherein the geographic condition of the link, in relation to the aerial network node is satisfied by one of: a position of the aerial network node relative to a constraint region; a coverage area of the aerial network node relative to a constraint region; a geographic location of the link between the aerial network node and the another node relative to a constraint region; and a geographic location of at least a portion of the link between the aerial network node and the another node relative to a constraint region.

3. The method of claim 1, wherein a geographic condition of the link between an aerial network node and another node, in relation to the aerial network node is satisfied when a predicted movement of the aerial network node as a function of time overlaps one of a cartographic region on Earth and constraint region defined by a mathematical function.

4. The method of any one of claims 1 to 3, wherein the aerial network node is a satellite and the another network node is one of: a ground station; and another satellite.

5. The method of any one of claims 1 to 4, wherein the determining is carried out by one of: a ground station; and a satellite.

6. The method of any one of claims 1 to 5, wherein the setting is carried out by one of: a ground station; and a satellite.

7. The method of any one of claims 1 to 6, wherein setting at least one attribute comprises setting one of: a downlink link attribute; an inter-satellite link (ISL) attribute; and a general operational attribute.

8. The method of any one of claims 1 to 6, wherein the at least one attribute of the link is one of: an intermediate system-to-intermediate system (ISIS) attribute; an open shortest path first (OSPF) attribute; a frequency attribute; a power attribute; a coding attribute; and a ground station address attribute.

9. The method of claim 1, wherein a geographic condition of the link between the aerial network node and another node, in relation to the aerial network node, is satisfied when at least one of: a location of the aerial network node with respect to the Earth overlaps a location of another set of infrastructure nodes at a higher or lower orbit; a location of the link with respect to the Earth overlaps a location of another set of infrastructure nodes at a higher or lower orbit; or a location of at least a portion of the link with respect to the Earth, overlaps a location of another set of infrastructure nodes at a higher or lower orbit.

10. The method of any one of claims 1 to 9, wherein setting at least one attribute of the link to match at least one attribute associated with the geographic condition comprises: creating a new link between the aerial network node and the another node having the at least one attribute. 15

11. The method of any one of claims 1 to 10, wherein: setting at least one attribute of the link to match at least one attribute associated with the geographic condition comprises modifying the link.

12. An aerial network node comprising: one or more processors; a memory storing instructions which, when executed by the one or more processors, cause the aerial network node to perform the method of any one of claims 1 to 11.

13. A computer-readable medium comprising when executed by the one or more processors of aerial network node, cause the aerial network node to perform the method of any one of claims 1 to 11.

14. A computer program comprising when executed by the one or more processors of aerial network node, cause the aerial network node to perform the method of any one of claims 1 to 11.